For many applications, it is desirable to have a light device that produces uniform illumination at and across a planar surface. Conventionally, with reference to FIGS. 1A and 1B, one approach utilizes parabolic optics 102 coupled to a light source 104 for capturing light emitted from the light source 104 and redistributing the light to generate a more homogeneous illumination distribution across the target region. Although the parabolic reflectors successfully capture a large portion of light from the source, the degree of illumination homogeneity generated by the parabolic reflector is unsatisfactory. For example, FIG. 1B shows several “hot spots” in a contour plot of illumination on a plane of area 2×2 m2 illuminated by the light device having the parabolic optics 102.
Referring to FIGS. 2A and 2B, another conventional strategy utilized for producing uniform illumination utilizes a V-shaped flat reflector 202 partially surrounding a light source (typically a fluorescent tube) 204. Although this light device may appear to provide improved illumination homogeneity (i.e., approximately 3:1 illumination variation across a region of area 2×2 m2) at a distance far from the device (e.g., 2 meters), at a shorter distance (e.g., 30 centimeters) from the light device, the illumination variation across the 2×2 m2 region, however, remains unsatisfactory (i.e., approximately 10:1) as illustrated in FIG. 2B. Additionally, placing the light device far away from the target region to improve the illumination homogeneity sacrifices overall intensity, thereby resulting in energy waste.
Accordingly, there is a need for illumination devices that effectively and efficiently illuminate a desired region uniformly.